1. Field of the Invention
The present invention relates to a recording material discrimination device, an image forming apparatus, and a method therefor, and more specifically, to a recording material discrimination device, an image forming apparatus, and a method for detecting reflected light from the surface of a recording material and the amount of transmitted light of the recording material and discriminates the kind thereof.
2. Description of the Related Art
An image forming apparatus such as a copier and a laser printer transfers an image visualized and developed by a developing part onto a recording material and fixes the developer image by heating and pressing the image in a predetermined fixing treatment condition. Since this predetermined fixing treatment condition largely differs depending on the quality of material, thickness, or surface treatment, or the like, when plural kinds of recording materials are used, detailed settings are necessary in response to the kinds of recording materials.
Conventionally, in such an image forming apparatus, for example, the size and kind of recording material (if the recording material is paper, the kind of paper) is set by a user using an operation panel provided on the main body of the image forming apparatus or the like, and the fixing treatment condition (e.g., fixing temperature or carrying speed of the recording material passing through the fixing device) is changed in response to the settings. Recently, technologies for further using a sensor for discriminating the recording materials within the image forming apparatus to automatically discriminate the kinds of recording materials and variably controlling developing conditions, transfer conditions, or fixing conditions in response to the discriminated kinds are proposed.
In the technologies for automatically detecting the kinds of recording materials, for example, a method for detecting surface smoothness of the recording material by imaging the surface image of the recording material by a CCD sensor and converting the information into fractal dimensional information, a method for discriminating the kind of paper from surface smoothness by imaging the surface image of the recording material by a CCD sensor or CMOS area sensor and detecting roughness of the recording material from the magnitude relation of the light, or a method for detecting the thickness of the recording material from the length formed at the end of the recording material are proposed (e.g., see Japanese Patent Application Laid-open No. 2002-182518).
Furthermore, a technology for changing fixing conditions or the like by measuring the amount of light transmitted through the recording material and determining the material thickness of the recording material based on the magnitude of the amount of light is proposed (e.g., see Japanese Patent Application Laid-open No. 2003-186264).
However, in the above method for detecting surface smoothness of the recording material, sometimes the recording material can not be determined correctly when the recording material having the same smoothness but in different compressed conditions of paper fiber, for example, plain paper and heavy paper are determined. In such a case, developing conditions, transfer conditions, or fixing conditions can not be set suitably for the recording paper, and thereby, a problem that fixiability is deteriorated occurs.
On the other hand, in the above method for determining the material thickness of the recording material, the smoothness of the surface of the recording material is unknown, accordingly, since glossy paper or the like is less transparent than plain paper, the material thickness of the glossy paper is determined as being thicker even when the thickness thereof is the same as the plain paper, and thereby, suitable condition setting can not be performed.
Furthermore, in spite of the recent variety of kinds of recording materials, demands for printing quality are increased, and accurate determination of various recording materials is demanded.
The invention is achieved in light of these problems, and objected to provide a recording material discrimination device, an image forming apparatus, and a method for automatically discriminating various kinds of recording materials and performing image formation in suitable conditions.